Incomplete discharge of waste materials into the environment is of concern due to its slow degradability, highly soluble and biomagnification features in animals and plants. Conventional treatment techniques include chemical precipitation, ion-exchange, reverse osmosis and combustion are effective but energy intensive and consumes huge amounts of chemicals which may give rise to secondary problems such as spillage, corrosion and toxicity. The application of biological approach notably from use of microorganisms is an interesting alternative. Microorganisms such as bacteria, yeast and algae are known to survive in waste-containing environments owing to its ability to reduce, accumulate, sequester, absorb and oxidize different types of waste materials into forms, mostly making it less soluble and easily precipitated, that is, less toxic to the environment. This monograph covers biological approaches to remediate waste generated from various industries such as petroleum, electronic, textile, electroplating and landfill site(s). The role of microbes in composting and anaerobic digestion processes is also discussed. Apart from this effectiveness of microbes living in legumes of plant to remediate toxic heavy metals are also reported.